Stacked capacitor with enhanced capacitance

ABSTRACT

A semiconductor device is provided. The semiconductor device includes a semiconductor substrate, a stacked structure and contact vias. The stacked structure includes a plurality of conductive layers, and two adjacent conductive layers are isolated from each other with at least one dielectric layer. The contact vias have different heights, and partially through the stacked structure. Each of the plurality of contact vias is electrically connected to a corresponding conductive layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 15/072,936,filed on Mar. 17, 2016, now allowed, which is incorporated by referencein its entirety.

BACKGROUND

Capacitive structures are used as electronic elements in integratedcircuits such as Logic devices, CMOS image sensors (CIS), radiofrequency integrated circuits (RFIC), monolithic microwave integratedcircuits (MMIC), and etc. Capacitive structures include, for example,metal-oxide-semiconductor (MOS) capacitors, p-n junction capacitors andmetal-insulator-metal (MIM) capacitors. For some applications, MIMcapacitors can provide certain advantages over MOS and p-n junctioncapacitors because the frequency characteristics of MOS and p-n junctioncapacitors may be restricted as a result of depletion layers that formin the semiconductor electrodes. An MIM capacitor can exhibit improvedfrequency and temperature characteristics.

An MIM capacitor includes a dielectric layer disposed between lower andupper electrode plates. The desired capacitance density is usuallyincreased with increased integrated circuit density in dimensionscaling. The capacitance density, however, may not be simply increasedby stacking more electrode plates due to the area loss resulted fromcontact vias for electrically connecting each of the electrode plates.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various structures are not drawn to scale. In fact, the dimensions ofthe various structures may be arbitrarily increased or reduced forclarity of discussion.

FIG. 1 is a flow diagram illustrating a method for forming a stackedcapacitor according to some embodiments of the present disclosure.

FIGS. 2A, 2B, 2C, 2D, 2E, 2F and 2G are cross-sectional views at one ofvarious operations of manufacturing a semiconductor device according tosome embodiments of the present disclosure.

FIG. 2H is a top view of a semiconductor device according to someembodiments of the present disclosure.

FIG. 3 is a flow diagram illustrating a method for forming a stackedcapacitor according to some embodiments of the present disclosure.

FIGS. 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H are cross-sectional views at oneof various operations of manufacturing a semiconductor device accordingto some embodiments of the present disclosure.

FIG. 4I is a top view of a semiconductor device according to someembodiments of the present disclosure.

FIG. 5 is a schematic diagram of a semiconductor device according tosome embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of elements and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper”, “on” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

As used herein, the terms such as “first” and “second” describe variouselements, components, regions, layers and/or sections, these elements,components, regions, layers and/or sections should not be limited bythese terms. These terms may be only used to distinguish one element,component, region, layer or section from another. The terms such as“first” and “second” when used herein do not imply a sequence or orderunless clearly indicated by the context.

In some embodiments of the present disclosure, a stacked capacitorincluding a plurality of electrode plates stacked in a verticaldirection is provided. The stacked capacitor includes a plurality ofcontact vias (also referred to as contact plugs) electrically connectedto the respective electrode plates. The contact via electricallyconnected to a lower plate is extended through an upper plate through avia hole. Compared with the area of the electrode plate, the area of thecontact via is extremely minute. Accordingly, the area of the upperplate is substantially identical to the area of the lower plate.Consequently, the capacitance density of the stacked capacitor isenhanced. In some embodiments, the stacked capacitor is an MIM(metal-insulator-metal) capacitor including a plurality of metal platesstacked in the vertical direction with capacitor dielectric layer(s)interposed therebetween.

In the present disclosure, the stacked capacitor can be used aselectronic elements in integrated circuits such as Logic devices, CMOSimage sensors (CIS), radio frequency integrated circuits (RFIC),monolithic microwave integrated circuits (MMIC) and any integratedcircuits with high density capacitance requirement.

FIG. 1 is a flow diagram illustrating a method for forming a stackedcapacitor according to some embodiments of the present disclosure. Themethod 100 begins with operation 110, in which a first conductive layer,a dielectric layer, a second conductive layer and a cap layer are formedin order over a semiconductor substrate. The method 100 proceeds withoperation 120, in which a first via hole extending through the caplayer, the second conductive layer and the dielectric layer is formed toexpose the first conductive layer, and a second via hole extendingthrough the cap layer is formed to expose the second conductive layer.The method 100 continues with operation 130 in which, a spacer coveringsidewalls and exposing a bottom of the first via hole is formed. Themethod 100 proceeds with operation 140, in which a first contact viacoupled to the first conductive layer in the first via hole, a secondcontact via coupled to the second conductive layer in the second viahole, and a third contact via coupled to the third conductive layer inthe third via hole are formed.

The method 100 is merely an example, and is not intended to limit thepresent disclosure beyond what is explicitly recited in the claims.Additional operations can be provided before, during, and after themethod 100, and some operations described can be replaced, eliminated,or moved around for additional embodiments of the method.

FIGS. 2A, 2B, 2C, 2D, 2E, 2F and 2G are cross-sectional views at one ofvarious operations of manufacturing a semiconductor device according tosome embodiments of the present disclosure, and FIG. 2H is a top view ofa semiconductor device according to some embodiments of the presentdisclosure. As depicted in FIG. 2A and operation 110 in FIG. 1, themethod 100 begins at operation 110 in which a first conductive layer 12,a dielectric layer 14, a second conductive layer 16 and a cap layer 18are formed over a semiconductor substrate 10. In some embodiments, thesemiconductor substrate 10 includes a bulk semiconductor substrate. Thebulk semiconductor substrate includes an elementary semiconductor, suchas silicon or germanium; a compound semiconductor, such as silicongermanium, silicon carbide, gallium arsenic, gallium phosphide, indiumphosphide, or indium arsenide; or combinations thereof. In someembodiments, the substrate includes a multilayered substrate, such as asilicon-on-insulator (SOI) substrate, which includes a bottomsemiconductor layer, a buried oxide layer (BOX) and a top semiconductorlayer. In still some embodiments, the substrate includes an insulativesubstrate, such as a glass substrate, a conductive substrate, or anyother suitable substrates.

In some embodiments, the material of the first conductive layer 12includes metal such as copper (Cu), aluminum (Al), tungsten (W), orother suitable metal or alloy. In some embodiments, the material of thefirst conductive layer 12 includes metal compound such as titaniumnitride (TiN), tantalum nitride (TaN), or other suitable metalcompounds. The first conductive layer 12 may be single-layered ormulti-layered structure. The first conductive layer 12 may be formedover the semiconductor substrate 10 by physical vapor deposition (PVD),chemical vapor deposition (CVD) or any other suitable operations.

In some embodiments, the material of the dielectric layer 14 may includehigh-k dielectric material (i.e., a dielectric material having adielectric constant greater than silicon dioxide). In some embodiments,the material of the dielectric layer 14 may include low-k dielectricmaterial (i.e., a dielectric material having a dielectric constant equalto or less than silicon dioxide). By way of examples, the material ofthe dielectric layer 14 includes silicon dioxide (SiO₂), silicon nitride(Si₃N₄), aluminum oxide (Al₂O₃), tantalum oxide (Ta₂O₅), titanium oxide(TiO₂), zirconium oxide (ZrO₂), hafnium oxide (HfO₂), lanthanum oxide(La₂O₃), strontium titanate (SrTiO₃) or any other suitable low-k orhigh-k dielectric materials. The dielectric layer 14 may be formed overthe first conductive layer 12 by atomic layer deposition (ALD), chemicalvapor deposition (CVD) or any other suitable operations.

In some embodiment, the second conductive layer 16 includes metal suchas copper (Cu), aluminum (Al), tungsten (W), or other suitable metal oralloy. In some embodiments, the material of the second conductive layer16 includes metal compound such as titanium nitride (TiN), tantalumnitride (TaN), or other suitable metal compounds. The second conductivelayer 16 may be single-layered or multi-layered structure. The secondconductive layer 16 may be formed over the dielectric layer 14 by PVD,CVD or any other suitable operations.

In some embodiments, the material of the cap layer 18 may includedielectric material such as silicon dioxide, silicon nitride, siliconoxynitride, undoped silicon glass (USG) or any other suitable high-k orlow-k dielectric materials. The cap layer 18 may be a single-layeredstructure or multi-layered structure. The cap layer 18 may be formedover the second conductive layer 16 by CVD, ALD or any other suitableoperations.

As depicted in FIG. 2B, the cap layer 18, the second conductive layer16, the dielectric layer 14 and the first conductive layer 12 arepatterned. In some embodiments, a resist layer 20 such as a photoresistlayer is formed over the cap layer 18. Then, the cap layer 18, thesecond conductive layer 16, the dielectric layer 14 and the firstconductive layer 12 exposed by the resist layer 20 are removed by dryetching. In some embodiments, the patterned first conductive layer 12 isconfigured as a lower electrode plate of an MIM capacitor, and thepatterned dielectric layer 14 is configured as a capacitor dielectriclayer, and the patterned second conductive layer 16 is configured as anupper electrode plate. The lower electrode plate and the upper electrodeplate of the MIM capacitor are patterned in the same patterningoperation, and thus have substantially the same area. The resist layer20 is subsequently removed.

As depicted in operation 120 of FIG. 1, a first via hole extendingthrough the cap layer, the second conductive layer and the dielectriclayer is formed to expose the first conductive layer, and a second viahole extending through the cap layer is formed to expose the secondconductive layer. In some embodiments, the first via hole and the secondvia hole are, but not limited to be, formed by the following operations.As depicted in FIG. 2C, another resist layer 22 such as a photoresistlayer is formed over the cap layer 18. The resist layer 22 has anopening 22H exposing a portion of the cap layer 18. Then, the cap layer18, the second conductive layer 16 and the dielectric layer 14 areetched through the opening 22H of the resist layer 22 to form a firstcontact via 24 partially exposing the first conductive layer 12. In someembodiments, the sidewall 24S of the first via hole 24 is substantiallyvertical. In some embodiments, the sidewall 24S of the first via hole 24is substantially inclined outwardly. The resist layer 22 is subsequentlyremoved.

As depicted in FIG. 2D, another resist layer 26 such as a photoresistlayer is formed over the cap layer 18. The resist layer 26 has anopening 26H exposing another portion of the cap layer 18. Then, the caplayer 18 is etched through the opening 26H of the resist layer 22 toform a second contact via 28 partially exposing the second conductivelayer 16. In some embodiments, the sidewall 28S of the second via hole28 is substantially vertical. In some embodiments, the sidewall 28S ofthe second via hole 28 is substantially inclined outwardly.Subsequently, the resist layer 26 is removed.

As depicted in operation 130, a spacer covering sidewalls and exposing abottom of the first via hole is formed. In some embodiments, the spaceris, but not limited to be, formed by the following operations. Asdepicted in FIG. 2E, an insulative layer 30 is formed on the cap layer18, a bottom 24B and sidewalls 24S of the first via hole 24, and on abottom 28B and sidewalls 28S of the second via hole 28. The material ofthe insulative layer 30 may include silicon dioxide, silicon nitride, orany other suitable insulative materials. The insulative layer 30 coversthe bottom 24B and the sidewalls 24S of the first via hole 24, and thebottom 28B and the sidewalls 28S of the second via hole 28, but does notfill up the first via hole 24 and the second via hole 28. In someembodiments, the insulative layer 30 is substantially conformal to thebottom 24B and the sidewalls 24S of the first via hole 24, and thebottom 28B and the sidewalls 28S of the second via hole 28. Theinsulative layer 30 may be formed by atomic layer deposition (ALD) sothat the insulative layer 30 has good step coverage. In someembodiments, the insulative layer 30 is formed by CVD, PVD or any othersuitable operations.

As depicted in FIG. 2F, the insulative layer 30 on the bottom 24B of thefirst via hole 24 is etched to form a first spacer 32 exposing the firstconductive layer 12, and the insulative layer 30 on the bottom 28B ofthe second via hole 28 is etched to form a second spacer 34 exposing thesecond conductive layer 16. In some embodiments, an anisotropic etchingsuch as a dry etching without a mask layer is performed to remove theinsulative layer 30 on the bottom 24B of the first via hole 24 and thebottom 28B of the second via hole 28, while the insulative layer 30 onthe sidewalls 24S and the sidewall 28S is preserved. The first spacer 32is configured as isolation between the second conductive layer 16 andthe first contact via to be formed.

As depicted in FIG. 2G-2H and in operation 140 of FIG. 1, a firstcontact via 36 coupled to the first conductive layer (lower electrodeplate) 12 is formed in the first via hole 24, and a second contact via38 coupled to the second conductive layer (upper electrode plate) 16 isformed in the second via hole 28. In some embodiments, the first contactvia 36 and the second contact via 38 are formed by forming a conductivelayer (not shown) over the cap layer 18 and in the first via hole 24 andthe second via hole 28. The conductive layer over the cap layer 18 isthen removed by, for example, etching or chemical mechanical polishing(CMP). The material of the first contact via 36 and the second contactvia 38 may include tungsten (W), copper (Cu), aluminum (Al), or anyother suitable conductive materials. Accordingly, a semiconductor device1 having a dual-layered stacked capacitor 1A is accomplished.

The first contact via 36 is extended through the cap layer 18, thesecond conductive layer 16 and the dielectric layer 14 to electricallyconnect the first conductive layer (lower electrode plate) 12 throughthe first contact via 24. The first spacer 32 is configured to isolatethe first contact via 36 from the second conductive layer 16. Theperimeter of first contact via 36 is surrounded by the cap layer 18, thesecond conductive layer 16 and the dielectric layer 14. In such a case,the area of the second conductive layer (upper electrode plate) 16 canbe substantially identical to the area of the first conductive layer(lower electrode plate) 12. Accordingly, only the area of the firstcontact via 36 is sacrificed, and the thus the capacitance density canbe enhanced.

FIG. 3 is a flow diagram illustrating a method for forming a stackedcapacitor according to some embodiments of the present disclosure. Themethod 200 begins with operation 210, in which a first conductive layer,a first dielectric layer, a second conductive layer, a second dielectriclayer, a third conductive layer and a cap layer are formed in order overa semiconductor substrate. The method 200 proceeds with operation 220,in which a first via hole extending through the cap layer, the thirdconductive layer, the second dielectric layer, the second conductivelayer and the first dielectric layer is formed to expose the firstconductive layer, a second via hole extending through the cap layer, thethird conductive layer and the second dielectric layer is formed toexpose the second conductive layer, and a third via hole extendingthrough the cap layer is formed to expose the third conductive layer.The method 200 continues with operation 230 in which, a first spacercovering sidewalls and exposing a bottom of the first via hole, a secondspacer covering sidewalls and exposing a bottom of the second via hole,and a third spacer covering sidewalls and exposing a bottom of the thirdvia hole are formed. The method 200 proceeds with operation 240, inwhich a first contact via coupled to the first conductive layer isformed in the first via hole, a second contact via coupled to the secondconductive layer is formed in the second via hole, and a third contactvia coupled to the third conductive layer is formed in the third viahole.

The method 200 is merely an example, and is not intended to limit thepresent disclosure beyond what is explicitly recited in the claims.Additional operations can be provided before, during, and after themethod 200, and some operations described can be replaced, eliminated,or moved around for additional embodiments of the method.

FIGS. 4A, 4B, 4C, 4D, 4E, 4F, 4G and 4H are cross-sectional views at oneof various operations of manufacturing a semiconductor device accordingto some embodiments of the present disclosure, and FIG. 4I is a top viewof a semiconductor device according to some embodiments of the presentdisclosure. As depicted in FIG. 4A and operation 210 in FIG. 3, themethod 200 begins at operation 210 in which a first conductive layer 52,a first dielectric layer 54, a second conductive layer 56, a seconddielectric layer 58, a third conductive layer 60 and a cap layer 62 areformed in order over a semiconductor substrate 10.

In some embodiments, the material of the first conductive layer 52includes metal such as copper (Cu), aluminum (Al), tungsten (W), orother suitable metal or alloy. In some embodiments, the material of thefirst conductive layer 52 includes metal compound such as titaniumnitride (TiN), tantalum nitride (TaN), or other suitable metalcompounds. The first conductive layer 52 may be single-layered ormulti-layered structure. The first conductive layer 52 may be formedover the semiconductor substrate 10 by physical vapor deposition (PVD),chemical vapor deposition (CVD) or any other suitable operations.

In some embodiments, the material of the first dielectric layer 54 mayinclude high-k dielectric material (i.e., a dielectric material having adielectric constant greater than silicon dioxide). In some embodiments,the material of the first dielectric layer 54 may include low-kdielectric material (i.e., a dielectric material having a dielectricconstant equal to or less than silicon dioxide). By way of examples, thematerial of the first dielectric layer 54 includes silicon dioxide(SiO₂), silicon nitride (Si₃N₄), aluminum oxide (Al₂O₃), tantalum oxide(Ta₂O₅), titanium oxide (TiO₂), zirconium oxide (ZrO₂), hafnium oxide(HfO₂), lanthanum oxide (La₂O₃), strontium titanate (SrTiO₃) or anyother suitable low-k or high-k dielectric materials. The firstdielectric layer 54 may be formed over the first conductive layer 52 byatomic layer deposition (ALD), chemical vapor deposition (CVD) or anyother suitable operations.

In some embodiment, the second conductive layer 56 includes metal suchas copper (Cu), aluminum (Al), tungsten (W), or other suitable metal oralloy. In some embodiments, the material of the second conductive layer56 includes metal compound such as titanium nitride (TiN), tantalumnitride (TaN), or other suitable metal compounds. The second conductivelayer 56 may be single-layered or multi-layered structure. The secondconductive layer 56 may be formed over the first dielectric layer 54 byPVD, CVD or any other suitable operations.

In some embodiments, the material of the second dielectric layer 58 mayinclude high-k dielectric material (i.e., a dielectric material having adielectric constant greater than silicon dioxide). In some embodiments,the material of the second dielectric layer 58 may include low-kdielectric material (i.e., a dielectric material having a dielectricconstant equal to or less than silicon dioxide). By way of examples, thematerial of the second dielectric layer 58 includes silicon dioxide(SiO₂), silicon nitride (Si₃N₄), aluminum oxide (Al₂O₃), tantalum oxide(Ta₂O₅), titanium oxide (TiO₂), zirconium oxide (ZrO₂), hafnium oxide(HfO₂), lanthanum oxide (La₂O₃), strontium titanate (SrTiO₃) or anyother suitable low-k or high-k dielectric materials. The seconddielectric layer 58 may be formed over the second conductive layer 56 byALD, CVD or any other suitable operations.

In some embodiment, the third conductive layer 60 includes metal such ascopper (Cu), aluminum (Al), tungsten (W), or other suitable metal oralloy. In some embodiments, the material of the third conductive layer60 includes metal compound such as titanium nitride (TiN), tantalumnitride (TaN), or other suitable metal compounds. The third conductivelayer 60 may be single-layered or multi-layered structure. The thirdconductive layer 60 may be formed over the second dielectric layer 58 byPVD, CVD or any other suitable operations.

In some embodiments, the material of the cap layer 62 may includedielectric material such as silicon dioxide, silicon nitride, siliconoxynitride, undoped silicon glass (USG) or any other suitable high-k orlow-k dielectric materials. The cap layer 62 may be a single-layeredstructure or multi-layered structure. The cap layer 62 may be formedover the third conductive layer 60 by CVD, ALD or any other suitableoperations. In some embodiments, the material of the cap layer 62 may bethe same as the first dielectric layer 54 or the second dielectric layer58. In some embodiments, the etching rate of the cap layer 62 isdistinct from the etching rate of the first conductive layer 52, thesecond conductive layer 56 and the third conductive layer 60. Also, theetching rate of the first dielectric layer 54 or the second dielectriclayer 58 is distinct from the etching rate of the first conductive layer52, the second conductive layer 56 and the third conductive layer 60. Insome embodiments, the etching selectivity of the cap layer 62 isidentical to or similar to the etching selectivity of the firstdielectric layer 54 or the second dielectric layer 58.

As depicted in FIG. 4B, the cap layer 62, the third conductive layer 60,the second dielectric layer 58, the second conductive layer 56, thefirst dielectric layer 54 and the first conductive layer 52 arepatterned. In some embodiments, a resist layer 64 such as a photoresistlayer is formed over the cap layer 62. Then, the cap layer 62, the thirdconductive layer 60, the second dielectric layer 58, the secondconductive layer 56, the first dielectric layer 54 and the firstconductive layer 52 exposed by the resist layer 64 are removed by dryetching. The patterned first conductive layer 52 is configured as alower electrode plate of an MIM capacitor, the patterned secondconductive layer 56 is configured as an intermediate electrode plate,the patterned third conductive layer 60 is configured as an upperelectrode plate, and the patterned first dielectric layer 54 and seconddielectric layer 58 are configured as capacitor dielectric layers. Thelower electrode plate, the intermediate electrode plate and the upperelectrode plate of the MIM capacitor are patterned in the samepatterning operation, and thus have substantially the same area. Theresist layer 64 is subsequently removed.

As depicted in operation 220 of FIG. 3, a first via hole extendingthrough the cap layer, the third conductive layer, the second dielectriclayer, the second conductive layer and the first dielectric layer isformed to expose the first conductive layer, a second via hole extendingthrough the cap layer, the third conductive layer and the seconddielectric layer is formed to expose the second conductive layer, and athird via hole extending through the cap layer is formed to expose thethird conductive layer. In some embodiments, the first via hole, thesecond hole and the third via hole are, but not limited to be, formed bythe following operations of FIGS. 4C-4E. As depicted in FIG. 4C, a firstresist layer 66 such as a photoresist layer is formed over the cap layer62. The first resist layer 66 has a first opening 66H1 and a secondopening 66H2 partially exposing the cap layer 62. Then, the cap layer62, the third conductive layer 60, the second dielectric layer 58 areetched through the first opening 66H1 of the first resist layer 66 toform a recess 68 partially exposing the second conductive layer 56, andetched through the second opening 66H2 of the first resist layer 66 toform a second contact via 70 partially exposing the second conductivelayer 56. The first resist layer 66 is subsequently removed.

As depicted in FIG. 4D, a second resist layer 72 such as a photoresistlayer is formed over the cap layer 62. The second resist layer 72 blocksthe second via hole 70. The second resist layer 72 has a third opening72H3 corresponding to the recess 68 and a fourth opening 72H4 partiallyexposing the cap layer 62. Then, the second conductive layer 56 isetched through the third opening 72H3 and the recess 68. In someembodiments, the second conductive layer 56 is removed by dry etchingwith a higher etching rate than the cap layer 62 and the firstdielectric layer 54, and the etching rate of the cap layer 62 and thefirst dielectric layer 54 are identical or similar. Accordingly, the caplayer 52 is nearly not etched during the etching of the secondconductive layer 56. Consequently, the etching of the second conductivelayer 56 can be controlled to stop at the first dielectric layer 54 andthe cap layer 62.

As depicted in FIG. 4E, another dry etching operation is performed toetch the first dielectric layer 54 through third opening 72H3 and therecess 68 to form a first via hole 74 exposing the first conductivelayer 52, and to etch the cap layer 62 through the fourth opening 72H4to form a third via hole 76 exposing the third conductive layer 60.Then, the second resist layer 72 is removed

As depicted in operation 230 of FIG. 3, a first spacer coveringsidewalls and exposing a bottom of the first via hole, a second spacercovering sidewalls and exposing a bottom of the second via hole, and athird spacer covering sidewalls and exposing a bottom of the third viahole are formed. In some embodiments, the first spacer, the secondspacer and the third spacer are, but not limited to be, formed by thefollowing operations of FIGS. 4F and 4G. As shown in FIG. 4F, aninsulative layer 78 is formed on the cap layer 52, a bottom 74B andsidewalls 74S of the first via hole 74, on a bottom 70B and sidewalls70S of the second via hole 70, and on a bottom 76B and sidewalls 76S ofthe third via hole 76. The material of the insulative layer 78 mayinclude silicon dioxide, silicon nitride, or any other suitableinsulative materials. The insulative layer 78 covers the bottom 74B andthe sidewalls 74S of the first via hole 74, the bottom 70B and thesidewalls 70S of the second via hole 70, and the bottom 76B and thesidewalls 76S of the third via hole 76, but does not fill up the firstvia hole 74, the second via hole 70 and the third via hole 76. In someembodiments, the insulative layer 78 is substantially conformal to thebottom 74B and the sidewalls 74S of the first via hole 74, the bottom70B and the sidewalls 70S of the second via hole 70 and the bottom 76Band the sidewalls 76S of the third via hole 76. The insulative layer 78may be formed by atomic layer deposition (ALD) so that the insulativelayer 78 has good step coverage. In some embodiments, the insulativelayer 78 is formed by CVD, PVD or any other suitable operations.

As depicted in FIG. 4G, the insulative layer 78 on the bottom 74B of thefirst via hole 74 is etched to form a first spacer 80 exposing the firstconductive layer 52, the insulative layer 78 on the bottom 70B of thesecond via hole 70 is etched to form a second spacer 82 exposing thesecond conductive layer 56, and the insulative layer 78 on the bottom76B of the third via hole 76 is etched to form a third spacer 84exposing the third conductive layer 60. In some embodiments, ananisotropic etching such as a dry etching is performed without a masklayer to remove the insulative layer 78 on the bottom 74B of the firstvia hole 74, the bottom 70B of the second via hole 70 and the bottom 76Bof the third via hole 76, while the insulative layer 70 on the sidewalls74S, the sidewalls 70S and the sidewall 76S is preserved.

As depicted in FIG. 4H-4I and in operation 240 of FIG. 3, a firstcontact via 86 coupled to the first conductive layer (lower electrodeplate) 52 is formed in the first via hole 74, a second contact via 88coupled to the second conductive layer (intermediate electrode plate) 56is formed in the second via hole 70, and a third contact via 90 coupledto the third conductive layer (upper electrode plate) 60 is formed inthe third via hole 76. In some embodiments, the first contact via 86,the second contact via 88 and the third contact via 90 are formed byforming a conductive layer (not shown) over the cap layer 52 and in thefirst via hole 74, the second via hole 70 and the third via hole 76. Theconductive layer over the cap layer 52 is then removed by, for example,etching or chemical mechanical polishing (CMP). The material of thefirst contact via 86, the second contact via 88 and the third contactvia 90 may include tungsten (W), copper (Cu), aluminum (Al), or anyother suitable conductive materials. Accordingly, a semiconductor device2 having a triple-layered stacked capacitor 2A is accomplished.

The first contact via 86 is extended through the cap layer 62, the thirdconductive layer 60, the second dielectric layer 58, the secondconductive layer 56 and the first dielectric layer 54 to electricallyconnect the first conductive layer (lower electrode plate) 52 throughthe first contact via 74. The second contact via 88 is extended throughthe cap layer 62, the third conductive layer 60 and the seconddielectric layer 58 to electrically connect the second conductive layer(intermediate electrode plate) 56 through the second contact via 70.

The first spacer 80 is configured to isolate the first contact via 86from the third conductive layer 60 and the second conductive layer 56.The perimeter of first contact via 86 is surrounded by the cap layer 62,the third conductive layer 60, the second dielectric layer 58, thesecond conductive layer 56 and the first dielectric layer 54. The secondspacer 82 is configured to isolate the second contact via 88 from thethird conductive layer 60. The perimeter of second contact via 88 issurrounded by the cap layer 62, the third conductive layer 60 and thesecond dielectric layer 58. In such a case, the area of the thirdconductive layer (upper electrode plate) 60 can be substantiallyidentical to the area of the second conductive layer (intermediateelectrode plate) 56, and the area of the second conductive layer(intermediate electrode plate) 56 can be substantially identical to thearea of the first conductive layer (lower electrode plate) 52.Accordingly, only the areas of the first contact via 86 and the secondcontact via 88 are sacrificed, and the thus the capacitance density canbe enhanced.

The number of stacked electrode plates of the stacked capacitor is notlimited to be two or three layers, and may be modified to more thanthree layers based on different requirement of capacitance.

FIG. 5 is a schematic diagram of a semiconductor device according tosome embodiments of the present disclosure. In some embodiments, thesemiconductor device 5 includes the stacked capacitor 3 formed over aninterconnection layer 4. The stacked capacitor 3 may be a dual-layeredstacked capacitor, a triple-layered stacked capacitor or a stackedcapacitor with more than three stacked layers of electrode plates. Insome other embodiments, the stacked capacitor 3 may be integrated withthe interconnection layer 4. For example, part of or all of the stackedelectrode plates may be formed along with the metallization layer(s) ofthe interconnection layer 4. In some other embodiments, the fabricationof the stacked capacitor may be integrated into back end of line (BEOL),front end of line (FOEL) or any stages of semiconductor fabrication.

In some embodiments of the present disclosure, the stacked capacitorincludes a plurality of contact vias electrically connected to therespective electrode plates. The contact via electrically connected to alower plate is extended through an upper plate through a via hole.Compared with the area of the electrode plate, the area of the contactvia is extremely minute. Accordingly, the area of the upper plate issubstantially identical to the area of the lower plate. Consequently,the capacitance density of the stacked capacitor is enhanced.

In some embodiments of the present disclosure, the method ofmanufacturing the semiconductor device requires two patterningoperations to form three via holes, and thus the manufacturing cost andprocess complexity are reduced.

In one exemplary aspect, a semiconductor device is provided. Thesemiconductor device includes a semiconductor substrate, a firstconductive layer, a second conductive layer, a dielectric layer, a caplayer, a first contact via and a second contact via. The firstconductive layer is over the semiconductor substrate. The secondconductive layer is over the first conductive layer. The dielectriclayer is between the first conductive layer and the second conductivelayer. The cap layer is over the second conductive layer. The firstcontact via is through the cap layer, the second conductive layer andthe dielectric layer, and electrically connected to the first conductivelayer. A bottom of the first contact via stops at an upper surface ofthe first conductive layer. The second contact via is through the caplayer, and electrically connected to the second conductive layer. Abottom of the second contact via stops at an upper surface of the secondconductive layer.

In another exemplary aspect, a semiconductor device is provided. Thesemiconductor device includes a semiconductor device, a stackedstructure and a plurality of contact vias. The stacked structureincludes a plurality of conductive layers, and two adjacent conductivelayers are isolated from each other with at least one dielectric layer.The contact vias have different heights, and are partially through thestacked structure. Each of the plurality of contact vias is electricallyconnected to a corresponding conductive layer of the plurality ofconductive layers.

In yet another aspect, a semiconductor device is provided. Thesemiconductor device includes a semiconductor device, a first conductivelayer, a second conductive layer, a dielectric layer, a cap layer, afirst contact via, a second contact via, and a spacer. The firstconductive layer is over the semiconductor substrate. The secondconductive layer is over the first conductive layer. The dielectriclayer is between the first conductive layer and the second conductivelayer. The cap layer is over the second conductive layer. The firstcontact via is through the cap layer, the second conductive layer andthe dielectric layer, and electrically connected to the first conductivelayer. The second contact via is through the cap layer, and electricallyconnected to the second conductive layer. The spacer covers sidewalls ofthe second contact via, and the first contact via is isolated from thesecond conductive layer by the spacer.

The foregoing outlines structures of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A semiconductor device, comprising: asemiconductor substrate; a first conductive layer over the semiconductorsubstrate; a second conductive layer over the first conductive layer; adielectric layer between the first conductive layer and the secondconductive layer; a cap layer over the second conductive layer; a firstcontact via through the cap layer, the second conductive layer and thedielectric layer, and electrically connected to the first conductivelayer, wherein a bottom of the first contact via stops at an uppersurface of the first conductive layer; and a second contact via throughthe cap layer, and electrically connected to the second conductivelayer, wherein a bottom of the second contact via stops at an uppersurface of the second conductive layer.
 2. The semiconductor device ofclaim 1, further comprising: a first spacer covering sidewalls of thefirst contact via and exposing the first conductive layer; and a secondspacer covering sidewalls of the second contact via and exposing thesecond conductive layer.
 3. The semiconductor device of claim 2, whereinthe first contact via is isolated from the second conductive layer bythe first spacer.
 4. The semiconductor device of claim 3, wherein thefirst contact via is surrounded by the cap layer, the second conductivelayer and the dielectric layer.
 5. The semiconductor device of claim 1,wherein an area of the second conductive layer is substantiallyidentical to an area of the first conductive layer.
 6. The semiconductordevice of claim 1, further comprising an interconnection layer betweenthe semiconductor substrate and the first conductive layer.
 7. Thesemiconductor device of claim 1, wherein the cap layer comprises anundoped silicon glass (USG) layer.
 8. A semiconductor device,comprising: a semiconductor substrate; a stacked structure comprising aplurality of conductive layers, and two adjacent conductive layers areisolated from each other with at least one dielectric layer; and aplurality of contact vias having different heights, and partiallythrough the stacked structure, wherein each of the plurality of contactvias is electrically connected to a corresponding conductive layer ofthe plurality of conductive layers.
 9. The semiconductor device of claim8, further comprising a plurality of spacers covering sidewalls of theplurality of contact vias, respectively.
 10. The semiconductor device ofclaim 9, wherein each of the plurality of contact vias is isolated fromother conductive layers of the plurality of conductive layers by acorresponding spacer of the plurality of spacers.
 11. The semiconductordevice of claim 8, wherein bottoms of the plurality of contact vias aredisposed at different levels.
 12. The semiconductor device of claim 8,wherein tops of the plurality of contact vias are disposed at the samelevel.
 13. The semiconductor device of claim 8, wherein the stackedstructure comprises a stacked capacitor.
 14. The semiconductor device ofclaim 8, further comprising an interconnection layer between thesemiconductor substrate and the stacked structure.
 15. The semiconductordevice of claim 8, further comprising a cap layer over the stackedstructure, wherein the cap layer surrounds sidewalls of a correspondingcontact vias of the plurality of conductive vias.
 16. A semiconductordevice, comprising: a semiconductor substrate; a first conductive layerover the semiconductor substrate; a second conductive layer over thefirst conductive layer; a dielectric layer between the first conductivelayer and the second conductive layer; a cap layer over the secondconductive layer; a first contact via through the cap layer, the secondconductive layer and the dielectric layer, and electrically connected tothe first conductive layer; a second contact via through the cap layer,and electrically connected to the second conductive layer; and a spacercovering sidewalls of the second contact via, wherein the first contactvia is isolated from the second conductive layer by the spacer.
 17. Thesemiconductor device of claim 16, wherein a height of the first contactvia is larger than a height of the second contact via.
 18. Thesemiconductor device of claim 16, wherein a bottom of the first contactvia is disposed on an upper surface of the first conductive layer. 19.The semiconductor device of claim 16, wherein a bottom of the secondcontact via is disposed on an upper surface of the second conductivelayer.
 20. The semiconductor device of claim 16, wherein an area of thesecond conductive layer is substantially identical to an area of thefirst conductive layer.